Recent microbiological studies have suggested the existence of a periodontal disease associated microflora constituted by elevated proportions of certain organisms in the endogenous microbiota. Previous investigations and preliminary studies in support of this application have demonstrated a collagenase elaborated by several of these organisms including Bacteroides melaninogenicus subspecies intermedius and melaninogenicus, Bacteroides asaccharolyticus and Actinobacillus species. While there is some evidence for the participation of both vertebrate and microbial collagenases in the connective tissue degradation characteristic of peridontal disease, basic information with respect to collagenolytic enzymes of dental plaque microorganisms is severely limited. Few surveys of suspected anaerobic peridontal pathogens for collagenolytic activity are available and those enzymes which have been identified remain essentially uncharacterized. Little information exists on cultural requirements, inducibility, mechanism of action, or immunologic identity of oral microbial collagenases and the synergistic action of these enzymes with vertebrate collagenases are unexplored. The present application is directed to the study of oral microbial collagenases, particularly those elaborated by Bacteroides and Actinobacillus, to provide basic information on the nature of these enzymes and to define their role in the pathogenesis of periodontal disease.